To take the whole company over the
river you need to make 13 rides (see solutions below).

This puzzle wasn't as easy as it might seem at first sight. So we've
received some wrong solutions as well. The main mistake of them was
that on one of the two islands there were situations with more bears
than humans at the same time (of course, the special bear is a bear
too). This isn't acceptable as in the description we can read:
"There can never be more bears than humans on either island or the
human will be killed."

Bear in mind that when a bear (or human) comes to an island he has to
be counted as one more bear (or human) on that island even if he still
is sitting in the boat.

Also we've got some solutions where more than one bear can row. This
was a wrong assumption since the description says: "One bear is a
special bear who can drive the boat."

Also we've received a funny answer like this:
"The special driver and another bear can go over on the boat while the
humans swim to the other island. Then one bear can go back with the
boat and get the other bear."

This is a solution to the
Humans and Bears problem. I would like to point out that I refer to
the islands as Island 1 = the island everyone starts on and Island 2 =
the destination island. Also, unless specified as the Special Bear I
mean a Non-special Bear.

The solution is as follows:
3 humans denote as H, special bear denote as S and the
other 2 bears denote as B.
(SBBHHH= )

S and B go over to another island. (BHHH = SB)
S rolls back alone.(SBHHH=B)

S and another B go over to the island.(HHH=SBB)
S rolls back alone again.(SHHH=BB)

2H roll over to the island. (SH=BBHH)
One B and H come back together.(SBHH=BH)

S and H roll over to another island.(BH=SBHH)
One B and H come back again.(BBHH=SH)

2 H roll over to the island.(BB=SHHH)
S comes back alone.(SBB=HHH)

S fetches B over to the island.(B=SBHHH)
S comes back alone again to fetch the last B to go
over. (SB=BHHH) then ( =SBBHHH).

4. Solution by Marie Sabbe

A normal bear and a human
cross. The human returns.
The other normal bear and the special bear cross, and the special bear
returns.
Two humans cross, and a human and a bear return.
A human and the special bear cross, and the human returns with a
normal bear.
The two humans cross, and the special bear returns.
The special bear and a normal bear cross, and the special bear
returns.
The special bear crosses with the last normal bear.